Abstract
Background/Purpose
The ORBIT I trial, a first-in-man study, was conducted to evaluate the safety and performance of the orbital atherectomy system (OAS) in treating de novo calcified coronary lesions.
Methods/Materials
Fifty patients were enrolled between May and July 2008 based on several criteria, and were treated with the OAS followed by stent placement. The safety and performance of the OAS were evaluated by procedural success, device success, and overall major adverse cardiovascular event (MACE) rates, including cardiac death, myocardial infarction (MI) and need for target lesion revascularization (TLR). Our institution enrolled and treated 33 of the 50 patients and continued follow-up for 5 years.
Results
Average age was 54 years and 91% were males. Mean lesion length was 15.9 mm. Device success was 100%, and average number of orbital atherectomy devices (OAD) used per patient was 1.3. Stents were placed directly after OAS in 31/32 patients (96.9%). All stents (average stent per lesion 1.1) were successfully deployed with 0.3% residual stenosis. The overall cumulative MACE rate was 6.1% in-hospital, 9.1% at 30 days, 12.1% at 6 months, 15.2% at 2 years, 18.2% at 3 years and 21.2% at 5 years (4 total cardiac deaths). None of the patients had Q-wave MIs. Angiographic complications were observed in 5 patients. No flow/slow flow due to distal embolization was observed.
Conclusions
The ORBIT I trial suggests that OAS treatment continues to offer a safe and effective method to change compliance of calcified coronary lesions to facilitate optimal stent placement in these difficult-to-treat patients.
1
Introduction
Calcified coronary lesions are common, with 38% of all lesions showing calcification as detected by angiography and 73% of all lesions showing calcification as detected by intravascular ultrasound (IVUS) . Calcific deposits are found more frequently and in greater amounts in elderly individuals and more advanced lesions .
Efforts to control coronary artery calcification (CAC) with medical therapy have not been successful. Despite advances in interventional equipment and techniques, the treatment of calcified coronary lesions continues to pose an ongoing challenge . Calcified lesions respond poorly to balloon angioplasty, increase the likelihood of procedural failure, and are associated with a high frequency of restenosis and target lesion revascularization (TLR) . Coronary calcification may impair stent delivery and expansion, and damage the polymer/drug coating, resulting in impaired drug delivery and predisposition to restenosis and stent thrombosis . Attempts to remedy incomplete stent expansion with aggressive high pressure balloon dilatation may result in coronary artery rupture .
As a remedy to this problem, lesion preparation may be recommended to facilitate coronary stent implantation in these difficult lesions. Another goal of lesion preparation is to reduce plaque shift and allow optimal stent expansion . Rotational atherectomy (RA) is one of the procedures used to modify calcified plaques and improve overall success of stent implantation, but distal embolization of debris from the procedure is a concern. The incidence of slow or no flow in these procedures has been reported to be 6% to 15% .
The Diamondback 360® Coronary Orbital Atherectomy System (OAS) (Cardiovascular Systems, Inc., St. Paul, MN), which has been used successfully to treat peripheral vascular stenosis, has also been evaluated for the treatment of calcified coronary lesions. The ORBIT I clinical trial was conducted to evaluate the safety and long-term results after OAS treatment of de novo calcified coronary lesions in adults. Initial, 6-month and 3-year results have been previously published. Here, we report on the 5-year follow-up of a subset of 33 patients enrolled at one of the participating centers.
2
Material and methods
The ORBIT I trial was a prospective, non-randomized, multi-center, feasibility study that evaluated the safety, performance and effectiveness of the OAS. A total of 50 patients were enrolled at 2 sites in India (New Delhi, n = 17; Ahmedabad, n = 33). One of the participating centers enrolled and followed 33 of these ORBIT I patients up to 5 years. Ethics committee approval was received and patients who gave written informed consent and met all inclusion and no exclusion criteria were enrolled. Inclusion and exclusion criteria have been previously described . Briefly, patients with de novo coronary lesions with stenosis ≥ 50% and < 100%, and at least 1 quadrant of calcification via IVUS were enrolled, and patients with prior percutaneous coronary intervention (PCI) or surgery or very recent myocardial infarction (MI) were excluded.
All procedures were performed electively and performed in the standard fashion. The procedure has been previously described . Device success was defined as final achievement of ≤ 50% residual stenosis of the target lesion after OAS use only (before stent placement or any other adjunctive treatment), without a device malfunction. Procedural success was defined as ≤ 20% residual stenosis after stent placement. Change (lesion modification) was based on pre- and post-diameter stenosis of lesions treated with OAS. Patients were followed at 30 days, 3 months, 6 months, 2 years, 3 years and 5 years post-index treatment. The safety of the OAS was evaluated by procedural success, device success, and overall major adverse cardiovascular event (MACE) rates, including cardiac death, MI and need for TLR. Reporting of angiographic complications consisted of no flow or slow flow due to distal embolization, abrupt or threatened closure of the treated vessel, spasm requiring any surgical intervention (which could not be resolved via medications), dissection, perforation and other events seen angiographically.
Data collected on study specific case report forms were analyzed. Continuous variables including age, lesion characteristics, and OAS treatment parameters are presented as mean ± SD. The categorical data, including angina class, number of vessels, stents, and cumulative MACE rates are presented by frequency and percentage of patients. Adverse events were judged by the investigators as to their relatedness to the study device and treatment procedure to be “not related”, “undetermined”, or “related”. Kaplan Meier survival probability estimates were determined. P-values were determined using GraphPad Prism Version 5.4; p < 0.05 was considered as statistically significant.
2
Material and methods
The ORBIT I trial was a prospective, non-randomized, multi-center, feasibility study that evaluated the safety, performance and effectiveness of the OAS. A total of 50 patients were enrolled at 2 sites in India (New Delhi, n = 17; Ahmedabad, n = 33). One of the participating centers enrolled and followed 33 of these ORBIT I patients up to 5 years. Ethics committee approval was received and patients who gave written informed consent and met all inclusion and no exclusion criteria were enrolled. Inclusion and exclusion criteria have been previously described . Briefly, patients with de novo coronary lesions with stenosis ≥ 50% and < 100%, and at least 1 quadrant of calcification via IVUS were enrolled, and patients with prior percutaneous coronary intervention (PCI) or surgery or very recent myocardial infarction (MI) were excluded.
All procedures were performed electively and performed in the standard fashion. The procedure has been previously described . Device success was defined as final achievement of ≤ 50% residual stenosis of the target lesion after OAS use only (before stent placement or any other adjunctive treatment), without a device malfunction. Procedural success was defined as ≤ 20% residual stenosis after stent placement. Change (lesion modification) was based on pre- and post-diameter stenosis of lesions treated with OAS. Patients were followed at 30 days, 3 months, 6 months, 2 years, 3 years and 5 years post-index treatment. The safety of the OAS was evaluated by procedural success, device success, and overall major adverse cardiovascular event (MACE) rates, including cardiac death, MI and need for TLR. Reporting of angiographic complications consisted of no flow or slow flow due to distal embolization, abrupt or threatened closure of the treated vessel, spasm requiring any surgical intervention (which could not be resolved via medications), dissection, perforation and other events seen angiographically.
Data collected on study specific case report forms were analyzed. Continuous variables including age, lesion characteristics, and OAS treatment parameters are presented as mean ± SD. The categorical data, including angina class, number of vessels, stents, and cumulative MACE rates are presented by frequency and percentage of patients. Adverse events were judged by the investigators as to their relatedness to the study device and treatment procedure to be “not related”, “undetermined”, or “related”. Kaplan Meier survival probability estimates were determined. P-values were determined using GraphPad Prism Version 5.4; p < 0.05 was considered as statistically significant.
3
Results
A total of 33 patients, enrolled at a single center between May and July 2008, were followed for 5 years. Patient demographics have been previously reported and are provided in Table 1 . Lesions were classified according to the ACC/AHA system as Type A (6%), Type B1 (33%), and Type B2 (61%). Mean lesion length was 15.9 mm. Table 2 shows the lesion characteristics in details.
| Baseline Characteristic | Observations n/N (%) |
|---|---|
| Average age (years; mean ± SD) | 54.4 ± 9.1 |
| Gender (males) | 30/33 (90.9%) |
| Ethnicity (Asian Indian) | 33/33 (100%) |
| Diabetes | 10/33 (30.3%) |
| Hypertension | 9/33 (27.3%) |
| Obesity | 15/33 (45.5%) |
| Smoking | 2/33 (6.1%) |
| Angina | 32/33 (97.0%) |
| Stable angina | 29/32 (90.6%) |
| Canadian Cardiovascular Society Angina class I | 12/32 (37.5%) |
| Canadian Cardiovascular Society Angina class II | 17/32 (53.1%) |
| Canadian Cardiovascular Society Angina class III | 3/32 (9.4%) |
| Percutaneous coronary intervention history (> 30 days prior to study) | 5/33 (15.2%) |
| Coronary bypass graft surgery (prior to study) | 1/33 (3.0%) |
| Procedural Information | Observations n/N (%) (n = 33) |
|---|---|
| Target Vessel | |
| Left anterior descending | 20/33 (60.6%) |
| Left circumflex artery | 7/33 (21.2%) |
| Right coronary artery | 6/33 (18.2%) |
| American College of Cardiology/American Heart Association (ACC/AHA) lesion class: | |
| Type A | 2/33 (6.1%) |
| Type B1 | 11/33 (33.3%) |
| Type B2 | 20/33 (60.6%) |
| Balloon angioplasty predilation prior to IVUS | 6/33 (18.2%) |
| Mean lesion length (mm), mean ± SD | 15.9 ± 4.5 |
| Reference vessel diameter (mm), mean ± SD | 3.2 ± 0.4 |
| Mean lumen diameter (mm), mean ± SD | 1.3 ± 1.2 |
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